Estonia lodged a protest with Moscow on Wednesday, saying a Russian aircraft had violated the Baltic country’s airspace, the foreign ministry said.“We have issued a diplomatic note to the Russian foreign ministry, asking for explanations over why a Russian airplane violated Estonia’s airspace,” Estonian foreign ministry spokeswoman Ehtel Halliste told AFP.A Russian Tu-154 jet, en route to the Russian Baltic enclave of Kaliningrad, violated the airspace of Estonia twice Tuesday, according to the Estonian military.The purpose of the flight could not be established, the military added.The Tu-154 was built as a passenger jet, but the aircraft involved was not on a regular passenger flight.The plane made two brief incursions into Estonian airspace near the Baltic Sea islands of Naissaar and Osmussaar, both north to the capital Tallinn, the military said.“It was not possible to establish contact with the plane,” said Andres Sang, spokesman for the Estonian military. “We notified the NATO air operations center in Germany of the incidents.”The airspace of the Baltic states of Estonia, Latvia and Lithuania is patrolled by a NATO air policing unit, based in Lithuania.Estonia and the other Baltic states, which all joined NATO and the European Union in 2004, have repeatedly protested over violations of their airspace by planes from Russia, which ruled them until the collapse of the Soviet Union 16 years ago.In April, relations plunged to their lowest point since 1991, when Estonia regained independence from Moscow, as Moscow reacted furiously to Tallinn’s decision to shift a city-centre Soviet-era war memorial to a military cemetery.For many Estonians, the monument was a painful symbol of almost five decades of Soviet occupation after World War II, but for Russians, including Estonia’s sizable Russian-speaking minority, the move was an affront to the memory of soldiers who died fighting the Nazis.